SEOUL, South Korea — HONG YOON-HEE had an extraordinary tale to tell, to anyone who would listen, about how he risked his life trying to save South Korea during a pivotal moment in the Korean War but was then condemned to death and had to flee to the United States.
Jean Chung for The New York Times
Pictures of Mr. Hong, from left, in the South Korean Army, a military academy and the North Korean Army.
His plan, he said, was to clear his name.
Last year, after years of scouring military archives in the United States and South Korea and filing petitions and lawsuits, Mr. Hong achieved that goal. In February, a court in Seoul overturned his 1950 conviction of treason for fighting for North Korea.
Mr. Hong, 83, said in an interview that his quest was only half over, however. Now, he wants to be recognized as a hero.
“For 63 years, I lived with the stigma of being a traitor,” said Mr. Hong, who lives in California but remains a South Korean citizen and has visited Seoul frequently. “The truth is I helped save South Korea during one of its most critical times.”
When North Korea invaded the South in June 1950, Mr. Hong was a sergeant in the South Korean Army. He was among those trapped in Seoul when President Syngman Rhee fled south and the Han River bridge was bombed behind him, cutting off the evacuation route.
Mr. Hong said he had been desperate to catch up with the retreating South Korean troops. A friend, who turned out to be an underground Communist, suggested that Mr. Hong join the advancing North Koreans and then defect to South Korea at the front line. So Mr. Hong approached the North Koreans, claiming to be a brother of the North Korean vice prime minister, Hong Myong-hee. (They were, in fact, distant cousins.)
By August, Mr. Hong’s North Korean unit was approaching the Pusan perimeter, the defense line American and South Korean troops had built around southeastern South Korea. Then one day, he said, he heard that the North Korean leader, Kim Il-sung, had ordered a general offensive in early September in an all-out attempt to break through the perimeter and win the war.
“I couldn’t wait,” Mr. Hong said. “I might be killed crossing the front lines, but if the North won the war, my identity would be exposed and that would be the end of me, too.”
ON the night of Aug. 31, 1950, he slipped away. The next morning, he saw South Korean soldiers and shouted that he had urgent information. He was debriefed for hours by an American intelligence officer.
On Sept. 11, after he had returned to his old South Korean unit, the military police accused him of being a Communist spy.
Mr. Hong was tortured and sentenced to death, but his lawyer, an old acquaintance, appealed to the judge, who reduced the sentence to life imprisonment.
He was released in 1955, two years after the war ended, but remained under police surveillance. In 1973, fearing arrest under newly tightened security laws, he and his wife moved to the United States, where he ran a supermarket and a restaurant.
“I didn’t tell even my wife about my past because I didn’t want to burden my family with the stigma,” he said. “I thought that the information I provided in 1950 must have turned out to be wrong and that was the reason I was punished.”
In 1994, Mr. Hong found out that the United States military’s official history of the Korean War credited a North Korean defector, Maj. Kim Song-jun, with providing the crucial information about the 1950 offensive. The South Korean military’s history also cited Major Kim, calling his tip “so well-timed that the U.S. Eighth Army could alert all front-line units to be prepared for the enemy attack.”
But the more Mr. Hong researched Major Kim, the more skeptical he became. Major Kim’s debriefing report said only that he “heard a general offensive was to start.” And that debriefing took place days after the offensive had begun.
Major Kim, who returned to the North in a prisoner exchange in 1953, “seemed to be getting the credit due to me,” Mr. Hong said.
In 2000, the South Korean government’s Institute for Military History Compilation admitted that citing Major Kim as the source of the warning was an error. Mr. Hong also found his 1950 court-martial records, which contained mistakes, too. In the section on his treason conviction, the records said that he had fought South Korean troops on Sept. 3, 1950. But by then, he was back with his South Korean unit.
Despite the errors in the records, in 2007, the South Korean Supreme Court rejected Mr. Hong’s appeal for a retrial, citing lack of evidence.
Then in 2011, in the archives at the National Institute of Korean History in Seoul, he found a 1954 memo by Lt. Col. Roy E. Appleman, who wrote part of the official American history of the war.
Colonel Appleman said in the memo that he learned from American intelligence sources that Mr. Hong defected on Sept. 1, 1950, and gave a report on a planned North Korean offensive, which was relayed to the Far East Command in Tokyo.
But Colonel Appleman also wrote that he could not find Mr. Hong’s records and thought that Mr. Hong had been executed. Unable to confirm his role, he decided to cite Major Kim instead “due to the urgency” of publication deadlines.
That memo proved crucial to winning the retrial that cleared Mr. Hong’s name. In its February verdict, the Seoul district court praised his “long struggle to shed light on the Korean War and prove his innocence.”
BUT should Mr. Hong be recognized as a war hero?
Lee Sang-yup, a Korean War veteran who made many television documentaries about the war, called Mr. Hong’s case “one of the most unusual stories from the war.”
“I believe the information he brought with him was important for the United Nations forces at a critical time of the war,” Mr. Lee said.
Lee Gi-yun, a novelist, said that when he first met Mr. Hong in 1995 he was “a distraught old man whose children had found out about his time in prison and demanded to know if he was indeed a traitor.”
“He said he wanted to leave a record of what he did even if the rest of the world didn’t recognize it,” Mr. Lee added.
The Institute for Military History Compilation said that the allied forces had already anticipated the North Korean offensive from their own intelligence reports. The institute’s historians said they could not assess Mr. Hong’s contribution until the debriefing records were found.
But Mr. Hong insists that after reading thousands of pages of prisoner-of-war debriefings, he was the only one who crossed the front lines 63 years ago with the crucial information at that critical time.
“I’m convinced that I was a savior to the allied forces,” he said.